Centering control type drill system for offshore structure

ABSTRACT

Disclosed herein is a centering control type drill system for offshore structures. The centering control type drill system is installed to be elevated in a derrick for offshore drilling and rotates a drill string. The centering control type drill system includes a motor providing rotational force for offshore drilling, a gear box unit placed below the motor and increasing the rotational force of the motor, a main rotary shaft placed below the gear box unit and rotating the drill string; an intermediate bracket provided to the gear box unit, a dolly bracket disposed to be elevated in the derrick, a first dolly arm retractably coupled between the dolly bracket and the intermediate bracket by a hinge, a second dolly arm retractably coupled between the dolly bracket and the intermediate bracket by a hinge, and a cylinder rotating the second dolly arm about the hinge.

BACKGROUND

1. Technical Field

The present invention relates to a centering control type drill system of an offshore structure, and more particularly, to a centering control type drill system of an offshore structure, in which a dolly arm has a retractable structure so as to precisely center a drill pipe, i.e., a drill string.

2. Description of the Related Art

With rapid industrialization and industrial development, usage of resources such as petroleum has been gradually increased and thus stable production and supply of oil have raised important issues at a national level.

For this reason, there has recently been developed a drill ship with drilling equipment economically proper to develop a minor limited oil field or a deep sea oil field that has been untapped due to economic infeasibility, as well as land drilling.

In conventional offshore drilling, there has been generally used a rig ship designed for offshore drilling or a stationary platform that must be transported by tugboats, and perform drilling in a state of being anchored at a predetermined location on the sea by a mooring device. In recent years, however, a so-called drill ship manufactured like a general ship is developed to have state-of-the-art drilling equipment and navigate under its own power, and is used in offshore drilling.

In the center portion of the rig ship or drill ship provided with a variety of drilling equipment for drilling for oil, gas, etc. under the sea bed, a moon pool is formed such that a drill string, that is, a riser or a drill pipe for drilling for oil, gas, etc. under the sea bed can be moved up and down.

FIG. 1 is a side view showing drilling operation of a typical drill ship.

Referring to FIG. 1, a riser 3 and a drill pipe 4 are moved forward and downward through a moon pool 2 formed at the center of the drill ship, and then drill for seabed resources in an oil well 12 placed in a reservoir 11 under the seabed 5.

The riser 3 is a member that moves forward to the sea bed 5 before moving the drill pipe 4 to the oil well 12 and provides a passage through which mud returns.

With the riser 3 placed outside the drill pipe 4, the drill pipe 4 is moved down to the oil well 12 through a sub-bottom stratum 10 along the riser 3.

On the seabed 5, a blowout preventer (BOP) 6 is placed to prevent transfer of abnormal high pressure along the drill pipe 4.

In the sub-bottom stratum 10, a casing 7 is secured and a drill pipe 4 provided with a drill bit 9 is inserted into the casing 7 and drills for the seabed resources.

To prevent the drill bit 9 from overheating by heat generated when the drill bit 9 drills the ground and to facilitate drilling through lubrication, mud 8 is inserted into the drill pipe 4. The mud escapes through the drill bit 9 and returns through the casing 7 and the riser 3.

When the drilling operation is completed, the drill pipe 4 is moved to a drill floor through the moon pool 2, separated, and then carried to a loading place.

FIG. 2 is a view of a typical derrick and drill system.

Referring to FIG. 2, a typical drill ship includes an upper deck 13 and a drill floor 14 placed on the upper deck 13. The derrick 1 is placed on the drill floor 14. The drill string, for example, the drill pipe 4, transversely loaded in a pipe loading area is erected and gripped by a top drive 15 and a rotary table 16.

At least two drill pipes 4 are coupled to each other by rotational force supplied from the top drive 15, and drill the seabed.

In addition, in the typical drill system used in drilling operation, a dolly arm is rotatably coupled to a dolly frame by a hinge. However, the dolly arm has a monolithic structure that cannot be retractable, thereby making it difficult to achieve center alignment of the drill pipe.

BRIEF SUMMARY

The present invention has been conceived to solve such problems in the related art, and an aspect of the present invention is to provide a centering control type drill system for offshore structures, in which a dolly arm has a retractable structure such that center alignment of a drill pipe can be precisely and automatically adjusted upon drilling of multiple holes, thereby improving efficiency of drilling operation.

In accordance with one aspect of the present invention, a centering control type drill system for offshore structures, which is installed to be elevated in a derrick for offshore drilling and rotates a drill string, includes a motor providing rotational force for offshore drilling; a gear box unit placed below the motor and increasing the rotational force of the motor; a main rotary shaft placed below the gear box unit and rotating the drill string; an intermediate bracket provided to the gear box unit; a dolly bracket disposed to be elevated in the derrick; a first dolly arm retractably coupled between the dolly bracket and the intermediate bracket by a hinge; a second dolly arm retractably coupled between the dolly bracket and the intermediate bracket by a hinge; and a cylinder rotating the second dolly arm about the hinge.

The first dolly arm may include an upper dolly arm placed at an upper portion of the dolly bracket, and the second dolly arm may include a lower dolly arm placed at a lower portion of the dolly bracket.

The first dolly arm may include an arm housing having a hollow structure, coupled to the dolly bracket by the hinge, and formed with a plurality of locking holes on an outer circumference thereof in a longitudinal direction thereof; and an arm rod coupled to the intermediate bracket by the hinge, disposed to be slidably inserted into the arm housing, and provided with a locking projection formed on an outer circumference thereof in a longitudinal direction thereof and resiliently inserted into the locking hole.

The second dolly arm may include an arm housing having a hollow structure, coupled to the dolly bracket by the hinge, and formed with a plurality of locking holes on an outer circumference thereof in a longitudinal direction thereof; and an arm rod coupled to the intermediate bracket by the hinge, disposed to be slidably inserted into the arm housing, and provided with a locking projection formed on an outer circumference thereof in a longitudinal direction thereof and resiliently inserted into the locking hole. The locking projection may be resiliently disposed on a spring.

As described above, the dolly arm according to the present invention has a retractable double structure such that center alignment of the drill pipe can be precisely and automatically adjusted upon drilling of multiple holes, thereby improving efficiency of drilling operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the present invention will become apparent from the following description of embodiments given in conjunction with the accompanying drawings, in which:

FIG. 1 is a side view showing drilling operation of a typical drill ship;

FIG. 2 is a view of a typical derrick and drill system;

FIG. 3 is a perspective view of a centering control type drill system of an offshore structure according to one exemplary embodiment of the present invention;

FIG. 4 is a plan view of the centering control type drill system of FIG. 3;

FIG. 5 is a bottom view of the centering control type drill system of FIG. 3;

FIG. 6 is a side view showing a retraction mode in the centering control type drill system according to the exemplary embodiment of the present invention;

FIG. 7 is a side view showing a drilling mode in the centering control type drill system according to the exemplary embodiment of the present invention;

FIG. 8 is a view of a coupling structure of an arm housing and an arm rod of a dolly arm according to one exemplary embodiment of the present invention;

FIG. 9 is a view illustrating a structure of the dolly arm;

FIG. 10 is a cross-sectional view of an alternative example of a structure where a locking projection of the arm rod is coupled to a locking hole of the arm housing; and

FIG. 11 is a view of a coupling structure of an arm housing and an arm rod of a dolly arm according to another exemplary embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a perspective view of a centering control type drill system of an offshore structure according to one exemplary embodiment of the present invention; FIG. 4 is a plan view of the centering control type drill system of FIG. 3; FIG. 5 is a bottom view of the centering control type drill system of FIG. 3; FIG. 6 is a side view showing a retraction mode in the centering control type drill system according to the exemplary embodiment of the present invention; FIG. 7 is a side view showing a drilling mode in the centering control type drill system according to the exemplary embodiment of the present invention; FIG. 8 is a view of a coupling structure of an arm housing and an arm rod of a dolly arm according to one exemplary embodiment of the present invention; FIG. 9 is a view illustrating a structure of the dolly arm; and FIG. 10 is a cross-sectional view of an alternative example of a structure where a locking projection of the arm rod is coupled to a locking hole of the arm housing.

Referring to the drawings, a centering control type drill system for offshore structures according to one exemplary embodiment of the invention may be applied to any offshore structures and ships for drilling, and thus, the drill ship disclosed herein includes any kind of ship mounted with a drill system and capable of performing drilling operation.

According to the embodiment of the invention, the centering control type drill system 100 for offshore structures is installed to be elevated in a derrick 1 for offshore drilling, and rotates drill strings 4 (for example, drill pipes with a riser). The centering control type drill system 100 includes a motor 110 providing rotational force for offshore drilling; a gear box unit 120 placed below the motor 110 and increasing the rotational force of the motor 110; a main rotary shaft 130 placed below the gear box unit 120 and rotating the drill string 4; an intermediate bracket 140 provided to the gear box unit 120; a dolly bracket 150 disposed to be elevated in the derrick 1; a first dolly arm 160 retractably coupled between the dolly bracket 150 and the intermediate bracket 140 by a hinge H; a second dolly arm 170 retractably coupled between the dolly bracket 150 and the intermediate bracket 140 by the hinge H; and a cylinder 180 rotating the second dolly arm 170 about the hinge H. Herein, drill pipes will be described as one example of the drill strings 4.

To move the drill strings 4, that is, drill pipes, to an oil well and drill the seabed, many drill pipes are connected to each other and moved downward. Therefore, the motor 110 must provide power for connecting the drill pipes and power for drilling.

According to the present invention, the motor 110 is mounted on the system to provide strong rotational force to the drill strings, that is, the drill pipes 4, thereby making it possible to develop a deep-sea oil field.

The dolly bracket 150 is provided with a roller 152 such that the drill system can be moved up and down with respect to the derrick 1.

In the drill system according to this embodiment, the first dolly arm 160 and the second dolly arm 170 are disposed to achieve precise center alignment of the drill pipes.

In the present embodiment, a plurality of dolly arms may be provided. In the following description, the first dolly arm 160 and the second dolly arm 170 will be described as one example of the plurality of dolly arms.

The first dolly arm 160 refers to an upper dolly arm placed at an upper portion of the dolly bracket 150, and the second dolly arm 170 refers to a lower dolly arm placed at a lower portion of the dolly bracket 150.

The first dolly arm 160 includes an arm housing 161 having a hollow structure and coupled to the dolly bracket 150 by the hinge H; and an arm rod 162 coupled to the intermediate bracket 140 by the hinge H and disposed to be slidably inserted into the arm housing 161.

Further, the second dolly arm 170 includes an arm housing 171 having a hollow structure and coupled to the dolly bracket 150 by the hinge H; and an arm rod 172 coupled to the intermediate bracket 140 by the hinge H and disposed to be slidably inserted into the arm housing 171.

Specifically, the first dolly arm 160 includes the arm housing 161 having a hollow structure, coupled to the dolly bracket 150 by the hinge H, and formed with a plurality of locking holes 161 a on an outer circumference thereof in a longitudinal direction thereof; and the arm rod 162 coupled to the intermediate bracket 140 by the hinge H, disposed to be slidably inserted into the arm housing 161, and provided with a locking projection 162 a formed on an outer circumference thereof in a longitudinal direction thereof and resiliently inserted into the locking hole 161 a.

The arm rod 162 is inserted into the arm housing 161 and the locking projection 162 a is inserted into a locking hole 161 a to adjust the length of the first dolly arm 160. Then, the arm rod 162 and the arm housing 161 are fastened with a bolt B to set the overall length of the first dolly arm 160.

Likewise, the second dolly arm 170 includes the arm housing 171 having a hollow structure, coupled to the dolly bracket 150 by the hinge H, and formed with a plurality of locking holes 171 a on an outer circumference thereof in a longitudinal direction thereof; and the arm rod 172 coupled to the intermediate bracket 140 by the hinge H, disposed to be slidably inserted into the arm housing 171, and provided with a locking projection 172 a formed on an outer circumference thereof in a longitudinal direction thereof and resiliently inserted into the locking hole 171 a.

The arm rod 172 is inserted into the arm housing 171 and the locking projection 172 a is inserted into a certain locking hole 171 a to adjust the length of the second dolly arm 170. Then, the arm rod 172 and the arm housing 171 are fastened with a bolt B to set the overall length of the second dolly arm 170.

Referring to FIG. 10, the locking projection 162 a or 172 a is resiliently disposed on a spring 162 b or 172 b, such that the locking projection 162 a or 172 a can be smoothly coupled into the locking hole 161 a or 171 a by the spring 162 b or 172 b.

The drill system is provided with an elevator 193, a pipe handling unit 191, and the like below the gear box unit 120. The elevator 193 is a typical drilling apparatus configured to grip and fasten the drill pipes 4.

Tripping load is transferred to a travelling block 190 to support the weight of the derrick 1 to which the travelling block 190 is connected.

Next, operation of the centering control type drill system for offshore structures according to the exemplary embodiment of the present invention will be described.

The drill system is moved down by a wire (not shown) connected to the travelling block 190. Here, the roller 152 of the dolly bracket 150 serves as a guide for the derrick 1.

When drill strings 4, that is, drill pipes, are gripped and fastened by the elevator 193, the pipe handling unit 191 and a traction unit 192, the drill pipes are coupled to each other or drill the sea bed by rotational force from the motor 110.

In the drill system according to the present embodiment, the first dolly arm 160 and the second dolly arm 170 are provided to precisely adjust center alignment of the drill strings, in which the lengths of the first and second dolly arms 160, 170 are adjustable.

That is, the arm rod 162 is inserted into the arm housing 161 such that the locking projection 162 a can be inserted into a certain locking hole 161 a to adjust the length of the first dolly arm 160. Then, the arm rod 162 and the arm housing 161 are fastened by the bolt B, thereby properly adjusting and setting the overall length of the first dolly arm 160.

Further, the arm rod 172 is inserted into the arm housing 171 such that the locking projection 172 a can be inserted into a certain locking hole 171 a to adjust the length of the first dolly arm 170. Then, the arm rod 172 and the arm housing 171 are fastened by the bolt B, thereby properly adjusting and setting the overall length of the second dolly arm 170.

FIG. 11 is a view of a coupling structure of an arm housing and an arm rod of a dolly arm according to another exemplary embodiment of the present invention.

Referring to FIG. 11, the dolly arm according to this embodiment includes a first dolly arm 260 and a second dolly arm 270, and allows automatic length adjustment by a servomotor 263.

The first dolly arm 260 includes an arm housing 261 having a hollow structure, coupled to the dolly bracket 150 by a hinge H; an arm rod 262 coupled to an intermediate bracket 140 by the hinge H and disposed to be slidably inserted into an arm housing 261; and a servomotor 263 internally secured to the arm housing 261 and having a rotary shaft 263 a screw-coupled to a rear side of the arm rod 262.

The second dolly arm 270 includes an arm housing 271 having a hollow structure, coupled to the dolly bracket 150 by a hinge H; an arm rod 272 coupled to the intermediate bracket 140 by the hinge H and disposed to be slidably inserted into the arm housing 271; and a servomotor 273 internally secured to the arm housing 271 and having a rotary shaft 273 a screw-coupled to a rear side of the arm rod 272.

Next, operation the centering control type drill system for offshore structures according to this embodiment of the present invention will be described.

In the drill system according to this embodiment, the first dolly arm 260 and the second dolly arm 270 are provided to achieve precise adjustment of center alignment of drill pipes, that is, drill strings, in which the lengths of the first and second dolly arms 260, 270 can be automatically adjusted by the servomotors.

That is, in operation of the servomotor 263, a rotary shaft 263 a is rotated and screw-coupled to the rear side of the arm rod 262, whereby the arm rod 262 can slide into the arm housing 261, thereby properly adjusting and setting the overall length of the first dolly arm 260.

Further, in operation of the servomotor 273, a rotary shaft 273 a is rotated and screw-coupled to the rear side of the arm rod 272, whereby the arm rod 272 can slide into the arm housing 271, thereby properly adjusting and setting the overall length of the second dolly arm 270.

As described above, the dolly arm according to the present invention has a retractable double structure such that center alignment of the drill pipes can be precisely and automatically adjusted upon drilling of multiple holes, thereby improving efficiency of drilling operation.

Although the present invention has been illustrated with reference to some exemplary embodiments in conjunction with the drawings, it will be apparent to those skilled in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention. 

1. A centering control type drill system for offshore structures, which is installed to be elevated in a derrick for offshore drilling and rotates a drill string, the centering control type drill system comprising: a motor providing a rotational force for offshore drilling; a gearbox unit placed below the motor and increasing rotational force of the motor; a main rotary shaft placed below the gearbox unit and rotating the drill string; an intermediate bracket provided to the gearbox unit; a dolly bracket disposed to be elevated in the derrick; a first dolly arm retractably coupled between the dolly bracket and the intermediate bracket by a hinge; a second dolly arm retractably coupled between the dolly bracket and the intermediate bracket by a hinge; and a cylinder rotating the second dolly arm about the hinge.
 2. The centering control type drill system according to claim 1, wherein the first dolly arm comprises an upper dolly arm placed at an upper portion of the dolly bracket, and the second dolly arm comprises a lower dolly arm placed at a lower portion of the dolly bracket.
 3. The centering control type drill system according to claim 1, wherein the first dolly arm comprises an arm housing having a hollow structure, coupled to the dolly bracket by the hinge, and formed with a plurality of locking holes on an outer circumference thereof in a longitudinal direction thereof; and an arm rod coupled to the intermediate bracket by the hinge, disposed to be slidably inserted into the arm housing, and provided with a locking projection formed on an outer circumference thereof in a longitudinal direction thereof and resiliently inserted into the locking hole, and wherein the second dolly arm comprises an arm housing having a hollow structure, coupled to the dolly bracket by the hinge, and formed with a plurality of locking holes on an outer circumference in a longitudinal direction; and an arm rod coupled to the intermediate bracket by the hinge, disposed to be slidably inserted into the arm housing, and provided with a locking projection formed on an outer circumference thereof in a longitudinal direction thereof and resiliently inserted into the locking hole.
 4. The centering control type drill system according to claim 3, wherein the locking projection is resiliently disposed on a spring.
 5. The centering control type drill system according to claim 1, wherein the first dolly arm comprises an arm housing having a hollow structure and coupled to the dolly bracket by the hinge; an arm rod coupled to the intermediate bracket by the hinge and disposed to be slidably inserted into the arm housing; and a servomotor internally secured to the arm housing and having a rotary shaft screw-coupled to a rear side of the arm rod, and wherein the second dolly arm comprises an arm housing having a hollow structure and coupled to the dolly bracket by the hinge; and an arm rod coupled to the intermediate bracket by the hinge and disposed to be slidably inserted into the arm housing; and a servomotor internally secured to the arm housing and having a rotary shaft screw-coupled to a rear side of the arm rod.
 6. The centering control type drill system according to claim 1, wherein the dolly bracket comprises a roller.
 7. A centering control type drill system for offshore structures, which is installed to be elevated in a derrick for offshore drilling and rotates a drill string, the centering control type drill system comprising: a motor providing rotational force for offshore drilling; a gearbox unit placed below the motor and increasing the rotational force of the motor; a main rotary shaft placed below the gearbox unit and rotating the drill string; an intermediate bracket provided to the gearbox unit; a dolly bracket disposed to be elevated in the derrick; a plurality of dolly arms retractably coupled between the dolly bracket and the intermediate bracket by a hinge; and a cylinder rotating one of the dolly arms about the hinge.
 8. The centering control type drill system according to claim 7, wherein each of the dolly arms comprises: an arm housing having a hollow structure and coupled to the dolly bracket by the hinge; and an arm rod coupled to the intermediate bracket by the hinge and disposed to be slidably inserted into the arm housing. 